Mk7 GTI Throttle Charge Pipe Temperature Sensor

Mk7 GTI Intercooler Outlet Temperature

The temperature sensor that has been used to record the pre-turbocharger intake air temperature was relocated into the throttle charge pipe.  This is the hard pipe that is between the intercooler outlet and throttle body.  This particular charge pipe has a built-in water/methanol injection port that provides a good means for measuring the intercooler outlet temperature.

Mk7 GTI Throttle Charge Pipe Temperature Sensor
Throttle Charge Pipe Temperature Sensor

Given the location of this charge pipe being directly between the IC outlet and intake manifold inlet, the relatively short length of the pipe, and the straight shot from the sensor location to the intake manifold, the assumption was that the Intercooler Outlet Temperature as measured by the sensor would match closely with the Intake Air Temperature as reported by the GTI’s intake air temperature sensor that is located within the Intake Manifold.  I was wrong.

Mk7 GTI Afternoon Commute Air Temperatures
Afternoon Commute Air Temperatures

Wow, what a difference!  At the end of the cruise portion of the drive, roughly time 1200, the temperature exiting the Intercoolers (bi-cooler setup using an eBay FMIC plus Unitronic direct fit) is sitting at roughly 5 degrees over ambient.  Inside the intake manifold the temperature sensor there is reading 40 degrees over ambient.

I was expecting there to be some difference, but nowhere close to what was recorded.  The air temperature being reported by the vehicle sensor is well above the temperature of the air exiting the intercooler.

It seems that only when the vehicle enters a condition of high airflow that the IAT sensor begins to give a more accurate reading of air temperature.  The brief acceleration up to 50 mph around time 1400 shows the IAT sensor reading dropping closer to that of the sensor in the charge pipe.